1. Field of the Invention
The present invention relates to a transmission electron microscope (TEM) and to a method of observing TEM images.
2. Description of Related Art
A transmission electron microscope (TEM) is configured including an electron beam source, an illumination lens, a first objective lens, an objective aperture, a second objective lens (objective minilens), a selected area aperture, and a projector lens, as disclosed, for example, in JP-A-4-334858. The TEM permits observation of TEM images such as diffraction patterns and real space images of samples.
In such transmission electron microscopy, selected-area electron beam diffraction is known as one method of observing diffraction patterns of samples.
FIG. 26 is a cross section illustrating one example of operation of a conventional transmission electron microscope, generally indicated by reference numeral 1000, when a diffraction pattern of a sample is observed using selected-area electron beam diffraction.
As shown in FIG. 26, the transmission electron microscope 1000 has an electron beam source 1002 emitting an electron beam L which is directed at a sample S by the use of an illumination lens 1004, condenser aperture 1014, objective lens 1006, second objective lens 1008, projector lens 1010, and detector 1012. The resulting diffraction pattern of the electron beam is imaged using an objective lens 1006 and a projector lens 1010. A diffraction pattern of a selected area on the sample S can be observed by selecting the area using a selected area aperture 1016. A real space image of this area can be obtained from the condition where the diffraction pattern is obtained, by varying the operative conditions of the projector lens 1010 while holding the operative conditions of the objective lens 1006. Data indicating the relationship between the diffraction pattern and the real space image can be derived through the use of selected-area electron beam diffraction in this way.
However, in the aforementioned observation method, a strong magnetic field is applied to the sample because an objective lens is used. Consequently, where the sample is made of a magnetic material susceptible to the effects of a magnetic field, the internal state of the sample itself may be varied by the applied field. Therefore, there is the problem that in a case where the sample is susceptible to the effects of a magnetic field, the intrinsic state of the sample cannot be observed due to the effects of the magnetic field on the sample during observation.